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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 165 pumped from any on- or off-site groundwater sources for the Proposed Project, and no changes would be made to the permeability of surfaces as a result of the work. Although the Proposed Project could bore up to 200 feet below the slough or river bottom and into the groundwater basin, the boreholes would be backfilled with cement-bentonite grout in accordance with California regulations and industry standards (Water Well Standards, DWR 74-81 and 74-90), therefore no impact on groundwater supplies, recharge or sustainable management, would occur from the Proposed Project. c) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or through the addition of impervious surfaces in a manner which would: a. result in substantial on- or off-site erosion or siltation? No Impact. Ground disturbance due to the Proposed Project only includes the boreholes or CPT holes, and is temporary. Over-water borings would be separated from the water, fully contained within the casing. Therefore, it would not result in substantial on- or off-site erosion or siltation. While there would be no impact, implementation of Mitigation Measure MM AES-1 and MM AGR-1 would further avoid, minimize and/or reduce the potential for impacts. b. substantially increase the rate or amount of surface runoff in a manner which would result in on- or off-site flooding? No impact. The Proposed Project would not substantially increase the rate or amount of surface runoff in a manner which would result in on- or off-site flooding because soil investigation activities are minimal in ground disturbance area and are temporary in nature. Soil investigation activities would not require the addition of significant areas of impervious surface therefore no impacts to rates or amount of runoff would occur. c. create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff? No impact. The Proposed Project would not create or contribute to runoff water or provide additional sources of polluted runoff because no additional sources runoff would be generated by the Proposed Project. Bentonite drilling fluids are considered to have very little toxicity and are the industry standard used in accordance with California regulations (Water Well Standards, DWR 74-81 and 74-90), and would be fully contained within the casing. While there would be no impact, implementation of Mitigation Measures MM HYD-1, MM HAZ-1, and MM HAZ-2 would further avoid, minimize and/or reduce the potential for impacts.